I've never tried it (or had the urge to), but I would investigate the following before making that decision:
1) Armed robbers have been known to ambush vehicles in the outlying areas. Some people have been killed.
2) If you are caught with a gun, or even a round of ammunition, it will be very unpleasant and expensive for you.
3) The roads may not be of the quality you are used to in the states. Make sure all the suspension components are in tip-top shape, and prepare to go slowly and carefully. Trip pre-planning is a must!
4) Your insurance is useless there, and being without insurance is a serious crime there, so make sure you are covered adequately (I know there are companies providing 'Mexican Auto Insurance', so I presume RV insurance would be available as well).
5) Not all the gas is of the quality you are used to in the states. It would be wise to figure out ways to minimize the problems this could cause (I don't know of any such methods, although for sure I would make sure my vehicle had 2 tanks, and only fill 1 of them if the source was of unknown quality).
6) The government is more corrupt than you are probably used to, particularly the police departments. There have been cases where people have been 'arrested' for something, requiring their relatives to pay huge 'fines' to get them out of the medieval jails. You will want to not appear to be a rich target. You will also want to familiarize yourself with the 'law of the land', so you are at least aware of what you can do and cannot do.
7) I have no idea what repair/parts facilities are available there, or their honesty. If you don't have the skills to diagnose problems, and the spare parts and tools to repair the likely ones, you could be stranded and/or ripped off.
8) I wouldn't do it unless someone in my party was fluent in Spanish, and preferably well acquainted with the culture in Mexico. My only significant venture into Mexico was in the company of such a person, and his knowlege and contacts made for a very enjoyable trip. It would be good but not required, if everyone in the party had some Spanish.